(1) Field of the Invention
The present invention relates to a technology of computer aided design (CAD) for improving efficiency in a design work, and in particular, relates to a design support device for CAD to realize automatic recognition of associated design programs and automatic data transfer between the steps of a process of design.
(2) Description of the Related Art
In general, a process of designing electronic circuits may comprise three main steps of (1) circuit design, (2) simulation, and (3) packaging design.
In the "circuit design" step, conceptual circuit diagrams are drawn for each module which individually performs its function respectively, and connections of these modules are defined. In the "simulation" step, input/output signals to and from the modules are defined by describing in the form of timing charts.
In the "packaging design" step, physical elements such as logic ICs, memories etc. are arranged on a real print circuit board in accordance with the definitions which are made in the previous circuit design and simulation steps. Thus these steps are independent with each other such that the simulation step is carried out after completion of the circuit design step, and the packaging step is carried out lastly. Therefore, it takes a total number of hours of these three steps to design an electronic circuit.
In addition, the result of a preceding step (e.g. the circuit design step) is reflected to the succeeding step (e.g. the simulation step), so that the succeeding step can be started only after completion of the preceding step.
In this regard, the Japanese patent application laying open publication No. 2-48774 discloses a technology for control of version numbers of design data and hierarchical control for a CAD system. More particularly, according to this Japanese publication, when more than one designer are expected to make modifications to data of the same parts, any modification to the data made by one of the designers is immediately reflected to the data of the other designers, thus enabling simultaneous modification of the same design data to increase efficiency in the design work.
However, while this prior art is aimed as its principal object to unify data control, it is limited only to the same design step. For example, the unified data control can be applied only to the works in the circuit design step or in the packaging design step. To the contrary, the present invention is directed to unify data control through the entire design process in which a series of design works, for example, circuit design step--simulation step--packaging design step, are carried out step by step while keeping a certain time difference between the steps, but the Japanese publication is not intended to realize such unification of data control.
Referring to FIGS. 18 to 20, more details of such unified data control between the design steps will be described below.
FIG. 18 shows that a modification to hit symbols in the circuit design step may have an effect on a modification to elements in the packaging design step. This figure illustrates an example in which modification to the functions of a symbol in the circuit design step (left-hand side of the drawing) causes modification to the element in the packaging design step (right-hand side of the drawing). In order to put such modification under a unified control, it is necessary to accurately post the elements or parts corresponding to the symbols in a circuit diagram from the circuit design step to the packaging design step.
FIG. 19 shows another example in which modification to the inputs of particular external signals in the circuit design step (left side of the drawing) affects the timing charts in the simulation step (right side of the drawing). In order to unify the data control between these steps, it is necessary to accurately post the name of a signal corresponding to the external terminal I1 from the circuit design step to the simulation step.
FIG. 20 shows an example in which deletion of a particular symbol as shown in dotted line in the circuit design step (left-hand side of the drawing) is reflected to deletion of one of the parts in dotted line in the packaging design step. In this case, it is also necessary to accurately post name of the parts corresponding to the symbol from the circuit design step to the packaging design step.
The above mentioned Japanese publication did not take into consideration such unified data control between the design steps being carried out step by step. Also the invention of the publication is based on the assumption that a plural designers work under a single information processing system, and it does not give thought to what a CAD system should be in the future under the circumstances that, for example, a circuit designer, a simulation operator and a packaging designer work at each work station separately at remote locations.
In order to dissolve the above mentioned problems of the prior art, the present invention is directed to increase efficiency in the entire process of design in a computer aided design system.